Modular staircase system and kit for erecting a staircase

ABSTRACT

The present invention relates to a novel method and modular assembly for producing a staircase. The modular staircase allows one with little to no skill to quickly and easily order and install a modular staircase at reasonable cost with no specialized technical skill necessary.

COPYRIGHT NOTICE

A portion of the disclosure of this patent contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to staircases and their fabrication for use on a commercial or residential site. More particularly the present invention relates to a staircase system which is pre-configured and precision cut to selected specifications, off site, under factory conditions and comes to the installation site in the form of a kit with improved construction and assembly techniques for such modular staircase systems. In at least one embodiment the staircase of the present invention is at least partially curved.

2. Description of Related Art

Staircases are composed of a number of standard components. Where there is a curved stair involved, each step has a curved inner radius smaller that the curved outer radius. Staircases, including curved staircases, are either supported by walls underneath the staircase or supported by attachment to the walls on either side of the staircase or, in many cases, supported by a wall on one side and self supported on the other side. In some embodiments of staircases, the staircase is free-standing or self-supported, only being supported by the floors and the balconies they are attached to at the top and bottom of the staircase.

Staircases are constructed within a 3 dimensional space defined by the standard plane limitations of the 3 axes, X, Y and Z However, it is usual within the trade that 4 measurements are needed or at least taken when building a staircase. The X axis is the horizontal plane and relates to the width of the staircase. The width is usually predefined in blueprints or based on the space available or in some cases by the person ordering the staircase. Typically, there are standard widths in the trade and it is very common that widths of 42 and 48 inches are used for the standard staircase. One skilled in the art would be able to determine the width and allow for things such as edging railings and the like. The Y axis is the depth plane, and represents the measurement from the very front of the staircase to the back of the staircase and is called the run. The run of stairs is divided equally to produce a number of treads that fits within the space (often determined by statutory code). The Z axis is the vertical measurement and is the floor to floor measurement used to figure the height of the risers. The floor to floor measurement is referred to as the rise. One last measurement is usually made or determined called the rake. The rake is the diagonal line from the end of the rise (top floor) to the end of the run on the first floor where the stair starts. While this measurement can be determined from the rise and run, it is useful to have the measurement as a guide during building of the staircase. The actual measurements can be extremely difficult to determine, even by those of great skill in the art, especially in residential construction, because of the use of various floor to ceiling heights, building codes, variation in the thicknesses of materials, errors in wall placements and the general minute inaccuracies introduced into the area around the staircase during construction due to cutting and measuring accuracy limitations. Cutting errors in the construction of the staircase itself add even further difficulties in constructing a staircase.

In order to build a staircase in place first stringers are glued together by using glued together wooden laminate. The stringers are attached to the support wall and measurements are made for the riser and tread and notches which are hand cut into the edges of the stringers for receipt of the riser and tread across the stringers. Then measurements are taken on the individual stringers for fabricating the individual riser and tread members for the staircase. The complexity and precision entailed in this conventional staircase fabrication technique renders it, as a general rule, a method only usable by skilled woodworking artisans and not by a general construction contractor.

Many of the problems limitations and disadvantages of building a staircase in place have been attempted to be overcome by a wide variety of modular staircase systems. While each of them has some advantage over fabrication of a staircase in place, each retains much of the complexity at the onsite installation and thus may still not be satisfactory for installation by a contractor let alone a do-it-yourselfer.

In U.S. Pat. No. 4,413,460 to Gerlach, issued Nov. 8, 1983 there is disclosed do it yourself spiral staircase having a hollow steel tube. The individual treads are distributed along the column between spacer sleeves in an open type construction. While this is good for this type of staircase, it does not address the standard residential curved staircase made with natural products such as wood, lumber, stone, granite or slate. In U.S. Pat. No. 4,583,335 to Morellini, issued Apr. 22, 1986 there is disclosed a modular staircase system wherein the framework of the staircase is produced by assembly of modular components paired with the next in sequence so as to form a bearing structure for the single stair tread. The stairs and components are slotted and designed to be built up as you go however since the components are standardized they do not take into consideration variations in walls and the like and can easily not fit a given situation.

In U.S. Pat. No. 5,613,341 to Skillern issued Mar. 25, 1997 there is disclosed a modular method of producing a staircase comprising supply of one-piece stair modules each having a front and back wall wherein the modules are placed together. Likewise in U.S. Pat. No. 5,502,933 also to Skillern there is disclosed a modular staircase comprising stair modules which are all identical.

In U.S. Pat. No. 6,516,574 to Couture issued Feb. 11, 2003 there is a staircase comprising a permanent framing made of metallic stringers. In addition there is a plurality of non-wooden step supports adapted to be mounted to the stringers. This modular method relies heavily on non-wooded nontraditional support means and still has the difficulty in adjusting the staircase to size at the location do to the use of non-adjustable metallic pieces. Lastly in US published patent application number US2006/0156649 to Smith and filed Jan. 19, 2005 there is disclosed a modular stair case comprising longitudinal modules that are stacked together to longitudinally telescope together and form successive portions of a staircase. The amount of wood and alignment necessary for this method makes it almost impossible for someone without a great deal of skill to actually set in place.

There is still therefore a great need for a modular staircase system that once provided is easy to install by an unskilled or lightly skilled worker that will meet the needs of each individual situation for installing such a staircase.

SUMMARY OF THE INVENTION

It has been discovered in the present invention that a modular component comprising custom cut pieces with predrilled screw holes can be lined up and assembled in place by the do it yourselfer or other construction person desiring to assemble a staircase but having little skill in the area of such assembly. By cutting the pieces to a specific shape and providing a subtread plate each portion can be installed without the skill and trauma necessary for prior art modular staircase systems.

Accordingly, in one embodiment, the present invention relates to a component staircase with predrilled screw holes that can be aligned between parts. Each of the parts is custom made for the individualized staircase, predrilled so that all that is necessary is to align matching holes and nail or screw the pieces together to assemble the staircase in place.

In one embodiment the present invention relates to a premeasured kit of parts for a staircase assembly the parts comprising:

-   -   a) an inner skirt board having a selected number of steps;     -   b) an outer skirt board having a selected number of steps         corresponding to the inner skirt board;     -   c) a plurality of riser boards corresponding to the number of         steps;     -   d) a plurality of tread boards corresponding to the number of         steps;     -   e) a plurality of tread sub-support plates corresponding to the         number of steps;         wherein the tread sub-support plate is designed to coordinativly         attach the inner skirt board, the outer skirt board, the riser         board and the tread board and wherein the parts are predrilled         with attachment holes.

In another embodiment of the invention there is a system for providing a modular staircase assembly comprising:

-   -   a) measuring the space intended for the staircase;     -   b) manufacturing an inner skirt board, and outer skirt board,         tread, riser and tread sub-support plates to construct a         staircase to fit the measured space;     -   c) drilling attachment and alignment holes in the parts of b)         such that the parts can be aligned and coordinativly attached to         the tread sub support plates to form the staircase.

These and other objects of the present invention will be clear when taken in view of the detailed specification and disclosure in conjunction with the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a perspective view of an assembly of the invention showing the tread sub-support plate and its attachment without the tread attached.

FIG. 1 b is a perspective view of the complete assembly of an embodiment of the kit of parts of the invention.

FIG. 2 a is a perspective view of an assembly showing the attachment of a skirt board and tread sub-support plate to the skirt boards.

FIG. 2 b is an angle view of an optional cleat reinforcement for the tread sub-support plate.

FIG. 3 a is an underneath view showing the reinforcement cleat of FIG. 2 a.

FIG. 3 b is a side view of an assembly of the invention as seen through the inner skirt.

FIG. 3 c is a side view of an alternate assembly of the present invention.

FIG. 4 is a 3-dimentional wedge defining rake, run, rise and width of the staircase.

DETAILED DESCRIPTION OF THE INVENTION

The general description of the invention and how to manufacture and assemble the kit of parts of the present invention is stated in the Brief Summary above. This detailed description defines the meaning of the terms used herein and specifically describes embodiments in order for those skilled in the art to practice the invention. The above interests in successfully providing an easy to assemble kit of parts for a staircase can readily be seen from the disclosure which follows and are met by the present invention. This detailed description defines the meaning of the terms used herein and specifically describes embodiments in order for those skilled in the art to practice the invention.

As used herein the term “premeasured” or “measuring” refers to taking measurements on site where the staircase is to be assembled. The measurements include the X, Y and Z (i.e. the rise, run, width and rake) measurements sufficient to construct a staircase. Other measurements including height of the skirt boards, curve radius, selected woods, or any other measurement desired in constructing the staircase of the invention can also be made at the same time and are also included in the measurement process. The measurements will need to be of sufficient accuracy by one skilled in the art such that the staircase can designed and precut to be assembled and slid into place without significant adjustment of the parts of the kit. This includes appropriate adjustments for the errors, misalignments and the like in the space to be installed and as such each staircase becomes a custom production kit. Within reason measurements should be within a quarter inch or so in order to insure a good fit.

Skirt boards comprise the sides of the staircase and can be on a wall side supported by a wall or on an open side and self supported. The skirt boards have steps built into it to accommodate the riser boards, sub-support plate and tread of the present invention. The skirt boards are in general spaced such that they achieve the measured or desired width of the staircase.

In a straight staircase the inner and outer skirt boards are the skirt boards on either side of the staircase and the inner and outer skirt boards generally refer to the same thing just the opposite sides from one another. Where a staircase is curved the “inner skirt board” is the skirt board that forms the smaller radius on the curve and the “outer skirt board” is the skirt board that forms the larger radius of the curve.

Where the skirt board is on an open side it can have a supporting wall or otherwise be self supported. If the skirt board is on a closed side, that is, against the wall, the skirt board will be attached to a wall. So, therefore, staircases can be totally self supporting, have both sides supported by walls or have one side supported by a wall while the other side is self supported (as is frequently the case with curved staircases).

A skirt board is, in one embodiment, built up from pieces of quarter inch plywood to a thickness of about ¾ inch to attach to a wall. To make a skirt-board self supporting, additional layers of plywood are added to a thickness of around 2 to 3 inches, however one skilled in the art can make the skirt board as thick as necessary and using any kind of wood built up to a desired thickness that is within the skill in the art. Often times local code will determine the actual thickness of a supporting skirt board and one skilled in the art can make the appropriate adjustments in thickness as well as step height for the riser board (US national building codes allow a maximum of 8¼ inch in height for a riser board). Normally, each skirt board is as long as is necessary to go from a given floor to the next landing and a skirt board herein can mean multiple boards sufficient to go from the bottom to the top of the staircase. A ¾ inch skirt board gives the support to the staircase until walls are built under the staircase or the staircase is attached to the wall. The present invention also provides “temporary walls’ which are designed and pre-cut for each staircase kit. The temporary walls are used to support the staircase while it is being constructed and usually stay attached until the staircase can be attached to or supported by the permanent walls. In the case of self-supporting stairs (which can be both sides), the skirt boards are built thick enough to produce a beam thick enough to support the staircase between its start on the floor and where it attaches on the floor above. In the case of a curved staircase, the skirt boards would be appropriately curved by attaching them to the tread sub-support plate designed to meet the wall in most cases. Such measurements, in view of the disclosure herein, are within the skill in the art. One of the primary reasons for an embodiment using layers of thin plywood for the skirt boards rather than one solid piece is that these thinner pieces can easily be bent to the shape necessary for the staircase (especially when curved) either in the factory or when putting the kit of parts together and can be adjusted more easily to fit the given space of the staircase.

The skirt board, when attached to a wall is normally visible and larger than a self supporting skirt board which is positioned beneath the tread and risers. One skilled in the art would be able to size both self supporting and wall supporting skirt boards in view of the teaching herein.

As used herein the “riser boards” are the upright front board for each step that is positioned under each tread and between the two skirt boards. The “tread” boards are the piece of wood of a step that one actually steps on. In other words, the steps top portion. In the case of a straight staircase, the tread will be rectangular but in the case of a curved staircase the sides of the tread (and or the return ends as needed for the type and style of curve) will have an inner and outer radius corresponding to the curve in the staircase itself and the wall or area the staircase is curving around. In one embodiment the tread board can be notched into the skirt boards to facilitate alignment and prevent changes in the steps over time.

As used herein the “tread sub-support plates” is a secondary piece of wood or other supporting material positioned underneath each tread at the front section. It is also positioned between the skirt boards and the top of one riser board and the bottom of the riser board of the next step (rear) up the staircase. The tread sub-support plate has each of the other components attached to it by predrilled holes and appropriate fasteners such as wood screws or nails as well as additional glue which is used to hold the parts together and add additional strength by having more areas to screw and glue which the customer uses to assemble the premeasured kit of parts. The staircase can be built without the tread installed initially with the use of the tread sub-support plate. This also would allow for the use a material that are not normally considered structural materials for treads such as reclaimed antique heart pine that has nail and or spike holes as well as large loose knots and could not be used as a tread without the tread sub-support plate of the invention. By coordinativly attaching (screwing or nailing through the pre-drilled holes) and the gluing each of the pieces by the predrilled alignment/attachment holes, the various parts of the kit can be assembled. In a further embodiment, the risers are notched in a manner that accepts the skirt boards and this further adds to a secured construction. The tread can be installed as the stair is being constructed or further in the construction process with the use of the sub-tread plate. In the case of a curved staircase, the curve is formed or created as each of the parts is screwed together and the kit assembled. In the embodiment where notching is also used the parts can further be aligned quickly and easily without long terms problems due to swelling, shrinkage or shifting.

As used herein “coordinativly attach” refers to the process of manufacturing each of the parts of the staircase in such a manner that the parts will fit together to make a staircase. In one embodiment, the attachment of the parts is coordinated around attachment to the sub-tread plate. While a number of means have been taught in the past, the present invention relates to the novel use of holes that are predrilled and coordinativly attach the pieces of the staircase to the tread sub-support plate. In one embodiment numbered or otherwise indicated holes match with which other numbered or indicated holes to facilitate alignment and proper matching of parts. Notching of each or some of the parts can also be done to further assist in aligning, attaching and holding the pieces in position for gluing and screwing and nailing.

The terms “predrilled for alignment and attachment” refers to the drilling of holes in corresponding parts of the kit that will attach such that they not only will attach but also align properly upon assembly. In an additional embodiment, the parts, for example the tread and risers can be notched for an even better fit. Further information can be observed in the embodiments shown in the figures which follow. As used herein, “holes” refers to use of a drilling mechanism to place a hole for use in attachment of the wooden parts of the stairs. By aligning holes from two parts a nail, screw, staple or the like can be driven into the two aligned holes for attachment and to insure alignment. Optionally glue can be used between the parts to further strengthen the attachments. Again in an embodiment each piece is screwed into the sub-support plate. Normally, such holes are starter holes made slightly smaller than the nail or screw or the like to be used as an attachment means. Where attachment means such as bolts are used, the hole could be slightly bigger than the bolt to be threaded through the hole. The present invention thus produces a staircase kit of parts which is much easier to assemble than previous staircase kits, is as sturdy but in most cases uses far fewer parts and materials to assemble making it less complicated and easier to understand the assembly process.

In one embodiment, an additional feature will be an alignment attachment cleat that is positioned on the sub-tread plate that will further help align and attach the parts. The cleat can be a one by one or the like positioned between the tread sub-support plate and the riser. One embodiment is disclosed in the figures which follow. One skilled in the art could include other variations of the cleat alignment/attachment board as further shown in the drawings. The cleats of the invention could be attached by any convenient means such as nails, screws and construction glue.

The process for putting together the kit of parts of the invention starts with measuring the space for the staircase. The present invention requires that accurate measurements be taken of the space and the appropriate kit of parts for the staircase be drafted out and manufactured based on those plans. Given the kit of parts and the disclosure and drawings herein, one skilled in the art of staircase construction could easily make the appropriate measurements (within about ¼ inch of error) followed by manufacturing the inner and outer skirt board(s), the treads, risers and tread sub-support plates and such optional parts such as the cleats, returns and cove molding for each kit of parts. By drilling alignment /attachment holes then, one of very low skill need only align all the holes in corresponding parts and screw or nail or the like the parts in order to coordinativly assemble the kit of parts produced to form a staircase. In one embodiment, all parts are attached to the central tread sub-support plates. This method makes it possible to manufacture a large number of staircases quickly and easily without having to stand over the manufacture and installation of each staircase on location. It also releaves the manufacturer of the stairs of the assembly process for the staircase which now can be done on a do it yourself basis and even ordered through warehouse hardware stores and the like without fear of the normal problems associated with the building of a staircase, even from previously known kits of parts which will end up with a large cost savings to the eventual purchaser or user. In one embodiment, the holes are numbered or otherwise indicated matching such that matching holes have matching numbers allowing some one assembling the staircase to match the parts in the kit and easily assemble the parts without having to figure out which part goes with which other part. In yet another embodiment the kit of parts is supplied with written, CD or video instructions for assembling the kit of parts. In other embodiments the kit of parts includes an assembly instruction sheet that could also in another embodiment show drawings including exploded drawings of the staircase construction.

The parts of the kit of parts in the present invention can be made essentially entirely of wood (absent decorative or other functional attachments). However, the addition of the novel tread sub-support plate means the tread material could be other than wood such as granite, stone or slate. The type of woods, treads thicknesses, exact measurements and sizes of the steps, number of steps and other construction details is well within the skill in the art of staircase construction in view of the disclosure herein. It is also, in another embodiment possible to include wall plates curved for the proper radius of a curved staircase, bands for curved balconies, landing treads to match curved balconies, railings, returns trim and any other part associated with a staircase and the like with the kit of parts to further complete the staircase where desired.

Now referring to the drawings, FIG. 1 a is a view of the kit of parts of the present invention without the treads attached, the kit of parts having been partially assembled in this figure up to the point of addition of the treads. In this view, outer skirt 2 would be attached to a wall to support the staircase but the wall has been left out for clarity. In this view, the skirt 2 is shown as a 3 ply 2 a, 2 b and 2 c. Attached to both outer 2 the inner skirt 3 are three riser boards 5 and three tread sub-support plates 4. In the kit of parts, both of the skirt boards 2 and 3, the end of riser 5 and sub-tread plate 4 have holes drilled in the end of the boards with matching holes 10 (shown in FIG. 1 a for inner skirt 3 and 2 b for outer skirt 2) which match up and are screwed or nailed together with the use of wood and construction glues.

Likewise in FIG. 1 a the riser boards 5 are screwed to the tread sub-plate 4 with a series of predrilled holes 10 that have had screws or nails used to attach them. In one embodiment the holes 10 are in the upper front side 15 (showing placement for attachment to riser 5) of the riser board and on the long wide edge of the sub-plate (shown in another figure where riser 5 in FIG. 1 a, is predrilled with holes 10 at location 15 and are attached as in FIG. 2 b).

Also in FIG. 1 a the inner skirt board 3 is shown closest to the viewer in this embodiment and like the outer skirt 2 it has had holes 10 pre-drilled and the screws or nails used to attach it to the riser 5 and sub-support plates 4. This configuration would then be a supported and skirt board 2 attached to the wall while skirt board 3 would have a wall built underneath it, to be followed by attachment of the treads (see FIG. 1 b). Since the thickness is hidden in this view it is not shown however like the inner and outer skirt boards it would most likely be 3 ply.

FIG. 1 b is the kit of parts completely assembled into a staircase 1. Shown again is outer skirt 2 and inner skirt 3 which form the left and right halves of the supported staircase 1. Risers 5 can also be seen in this figure. In this embodiment, however, the sub-support plate 4 is not seen since tread 6 with attached return 21 now sits on top of it and has been glued and screwed or the like in place. In an alternate embodiment, not shown the sub-plate 4 shown in FIG. 1 is attached to the tread 6 first and then attached to the rest of the components of the kit. One teaching a customer to build the kit of parts into staircase 1 could easily design the parts to be assembled in a number of different orders as long as the proper alignment/attachment holes 10 have been drilled. As can now be seen, the present invention will be much simpler to assemble than any of their previous modular staircases and will be as simple to build on site as in the stair masters shop.

FIG. 2 a is a view of the kit of parts with only a few of the pieces of staircase 1 in place while assembling the kit of parts. Outer skirt 2 is shown but in this view holes 10 are shown which correspond to the edge of the sub-plate board 4 and riser board 5. The tread 6 from FIG. 1 can be screwed or nailed from the bottom (as to hide attachment) right into the sub-plate 4 and/or the riser 5. In an alternate embodiment, the tread 6 can be attached to both of the skirts in a manner similar to all the other attachments. In this view the hidden edges of the boards can be seen. The front edge of the sub-plate 30, the top edge of riser 31, the top edge of inner skirt 32 and the front edge of inner skirt 33 (where the riser is attached) can all be seen in the view of the incomplete staircase 1.

FIG. 2 b shows an isolated riser 5 attached to a sub-support plate 4. Shown are the alignment attachment holes 10 as in previous views. In this view however, the edge of riser 51 which, in an embodiment, is notched to accept skirt board 3, is shown as is the edge of sub-plate 52. Accordingly, the alignment attachment holes 10 previously hidden are shown. In this view, optional cleat 20 is shown forming support between the riser 5 and sub-support plate 4 further strengthening the staircase construction in anticipation of addition of the tread 6. The cleats can be extremely important when the tread material is other than wood which cannot be screwed in for attachment such as stone, granite or slate. The cleat 20 in this embodiment is the entire length of the skirt 5 and sub-plate 4 interface but one skilled in the art can determined a desired length from the disclosure here. Further, the cleat 20 can be pre-attached to either the riser or sub-support plate to aid in alignment and attachment of the parts.

FIG. 3 a shows a view of the underneath of an embodiment of a portion of the assembled kit of parts of the invention wherein the cleat 20 is shown in another embodiment attaching to the sub-support plate 4 and riser 5. In this embodiment, the cleat does not extend the entire length of the attachment position of the two pieces of the kit but still acts as an extra support and alignment means. Other cleats can be seen in this embodiment a skirt/sub-tread plate cleat 24 is shown as is skirt/riser cleat 22. As with the other cleats shown the cleat adds strength and alignment features to the present kit.

FIG. 3 b shows a side view of a portion of the assembled kit of parts. The view in FIG. 3 b is as seen from the outer skirt 2 side, and for purposes of this view, the outer skirt 2 is drawn as if transparent. As can be seen in this view, a series of risers 5 attach to a series of sub-support plates 4 by alignment of holes 10. A screw 11 is shown attaching the two pieces that has been threaded through the two holes 10. In this embodiment tread 6 is aligned and attached to the sub-support plate and due to the molding 60 on tread 6, the screw 11 and screw hole 10 are hidden from view after assembly of the staircases.

FIG. 3 c shows yet another embodiment of the present invention. FIG. 3 c is a side view embodiment showing two steps without the inner and outer skirt boards. In this view treads 6 are shown again sitting on top of two each tread sub-support plate 4. Risers 5 are also shown from the side as well. In this view there is a cross-section of a riser/sub-support plate cleat 20 and a riser/skirt-board backing cleat 23. Also shown is a cross section of cove molding 60 which hides the screws 11 from view. The other alignment/attachment holes are left out for clarity but would be made as in FIGS. 1 a and 1 b or as one skilled in the art sees fit for example putting holes in the side of tread 6 for attachment to corresponding holes in the skirt boards.

In FIG. 4 there is shown a 3 dimensional wedge depicting the basic measurement characteristics of a staircase. The width is shown as 72 and is the width of the staircase between risers. The run 71 of the staircase is the front to back measurement of the staircase. The staircase height 70 is the distance between floors r the overall height of the staircase and lastly the staircase rake 73 is the diagonal formed by the staircase.

When the kit of parts is provided to the eventual purchaser, all the parts are essentially flat boards. They can be stacked, numbered, and tied together for ease of transport and for keeping the kit of parts organized. Since the kit can be transported in less space, the cost of transporting the staircase is substantially less than previous staircase kits. As described earlier, the parts can be coordinativly numbered in order to facilitate the assembly by one not skilled in the art of assembly of a staircase. In one embodiment, one could number the parts and then instruct the assembler how to match the numbers to construct a staircase.

As can be seen from the partial and complete construction view of the kit of parts, once provided with the kit, one can align and attach each of the pieces in a sequential manner to build an entire staircase of the desired size. One skilled in the art would not be limited by the specific examples and would be able to vary the size number etc of the staircase corresponding to the scope of the invention taught herein. Accordingly, the figures are not intended to be limiting the claims that follow.

The above description and example are for the purpose of teaching the person of ordinary skill in the art how to practice the present invention and it is not intended to detail all those obvious modifications and variations of it which become apparent to the skilled worker upon reading the present invention description. It is intended, however, that all such modifications and variations be included within the scope of the present invention, which is defined by the following claims. The claims are intended to cover the claimed steps and components, in any sequence, consistent with the present invention that is effective to meet the objectives herein intended unless the context specifically indicates to the contrary. 

1. A premeasured kit of parts for a staircase assembly the parts comprising: a) an inner skirt board having a selected number of steps; b) an outer skirt board having a selected number of steps corresponding to the inner skirt board; c) a plurality of riser boards corresponding to the number of steps; d) a plurality of tread boards corresponding to the number of steps; e) a plurality of tread sub-support plates corresponding to the number of steps; wherein the tread sub-support plate is designed to coordinativly attach the inner skirt board, the outer skirt board, the riser boards and the tread boards and wherein the parts are predrilled with attachment and alignment holes.
 2. A kit of parts according to claim 1 wherein the staircase is curved.
 3. A kit of parts according to claim 1 wherein the sub-support plate is pre-attached to the tread.
 4. A kit of parts according to claim 1 which further comprises a sub-support plate cleat.
 5. A kit of parts according to claim 5 wherein the tread is made of a material which cannot be screwed or nailed to the tread sub-support plate.
 6. A kit of parts according to claim 1 wherein at least 2 of the parts are notched to fit together.
 7. A kit of parts according to claim 5 wherein the riser and the skirt boards are notched to fit together.
 8. A kit of parts according to claim 1 which further comprises a set of one or two temporary walls for constructing the staircase prior to construction of or attachment to permanent walls.
 9. A method of assembling the kit of parts of claim 1 comprising attaching the skirt boards and riser boards to the sub-support plate followed attaching the tread to the sub-support plate.
 10. A system for providing a modular staircase assembly comprising: a) measuring the space intended for the staircase; b) manufacturing an inner skirt board, and outer skirt board, treads, risers and tread sub-support plates to construct a staircase to fit the measured space; c) drilling attachment and alignment holes in the parts of b) such that the parts can be aligned and coordinativly attached to the tread sub-support plates to form the staircase.
 11. A system according to claim 10 wherein there is also provided one or more support cleats.
 12. A system according to claim 10 wherein the sub-support plate is pre-attached to the tread.
 13. A system according to claim 10 wherein at least 2 of the parts are notched to fit together.
 14. A system according to claim 10 comprising attaching the skirt boards and riser boards to the sub-support plate followed by attaching the tread to the sub-support plate.
 15. A system according to claim 10 wherein the tread is made of a material which cannot be nailed or screwed to the tread sub-support plate.
 16. A system according to claim 10 wherein the staircase is assembled by attaching the staircase to one or two temporary walls. 